Pdc bit having split blades

ABSTRACT

A drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a nose region, a shoulder region, and a gage region, at least one disjointed blade disposed on the bit face, the disjointed blade including a first section beginning proximate a central axis of the bit and extending less than full gage, and a second section beginning a selected distance from the central axis and extending to full gage, and a plurality of cutting elements mounted on the at least one disjointed blade is disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application, pursuant to 35 U.S.C. §119(e), claims priority to U.S. Provisional Application Ser. No. 61/083,851, filed Jul. 25, 2008. That application is incorporated by reference in its entirety.

BACKGROUND OF INVENTION

1. Field of the Invention

Embodiments disclosed herein generally relate to fixed cutter drill bits. In particular, embodiments disclosed herein relate to fixed cutter drill bits having a unique blade design.

2. Background Art

Historically, there have been two types of drill bits used drilling earth formations, drag bits and roller cone bits. Roller cone bits include one or more roller cones rotatably mounted to the bit body. These roller cones have a plurality of cutting elements attached thereto that crush, gouge, and scrape rock at the bottom of a hole being drilled. Several types of roller cone drill bits are available for drilling wellbores through earth formations, including insert bits (e.g. tungsten carbide insert bit, TCI) and “milled tooth” bits. The bit bodies and roller cones of roller cone bits are conventionally made of steel. In a milled tooth bit, the cutting elements or teeth are steel and conventionally integrally formed with the cone. In an insert or TCI bit, the cutting elements or inserts are conventionally formed from tungsten carbide, and may optionally include a diamond enhanced tip thereon.

The term “drag bits” refers to those rotary drill bits with no moving elements. Drag bits, often referred to as fixed cutter drill bits, are often used to drill a variety of rock formations. Drag bits include those having cutting elements or cutters attached to the bit body, which may be a steel bit body or a matrix bit body formed from a matrix material such as tungsten carbide surrounded by an binder material. The cutters may be formed having a substrate or support stud made of carbide, for example tungsten carbide, and an ultra hard cutting surface layer or “table” made of a polycrystalline diamond material or a polycrystalline boron nitride material deposited onto or otherwise bonded to the substrate at an interface surface. Thus, fixed cutter drill bits known in the art include polycrystalline diamond compact (PDC) bits.

The typical PDC bit includes a bit body which is made from powdered tungsten carbide infiltrated with a binder alloy within a suitable mold form. The particular materials used to form PDC bit bodies are selected to provide adequate toughness, while providing resistance to abrasive and erosive wear. The cutting elements used on these bits are typically formed from a cylindrical tungsten carbide “blank” or substrate. A diamond “table” made from various forms of natural and/or synthetic diamond is affixed to the substrate. The substrate is then generally brazed or otherwise bonded to the bit body in a selected position on the surface of the body.

A plurality of PDC cutters is mounted along the exterior face of the bit body in extensions of the bit body called “blades.” Each PDC cutter has a portion which typically is brazed in a recess or pocket formed in the blade on the exterior face of the bit body. The PDC cutters are positioned along the leading edges of the bit body blades so that as the bit body is rotated, the PDC cutters engage and drill the earth formation.

A known drill bit is shown in FIG. 1. Bit 10 is a fixed cutter bit, and is preferably a PDC bit adapted for drilling through formations of rock to form a borehole. Bit 10 generally includes a bit body having shank 13, and threaded connection or pin 16 for connecting bit 10 to a drill string that is employed to rotate the bit for drilling the borehole. Bit 10 further includes a central axis 11 and a cutting structure on the face 14 of the drill bit, preferably including various PDC cutter elements 40 on a plurality of blades extending radially from the center of the cutting face. Also shown is a gage pad 12, the outer surface of which is at the diameter of the bit and establishes the bit's size. Thus, a 12″ bit will have the gage pad at approximately 6″ from the center of the bit.

Referring to FIG. 2, a profile of bit 10 is shown as it would appear with all blades and all cutter elements (including primary cutter elements and backup cutter elements) rotated into a single rotated profile. As shown, in rotated profile the plurality of blades of bit 10 includes blade profiles 39. Blade profiles 39 and bit face 20 may be divided into three different regions labeled cone region 24, shoulder region 26, and gage region 28. Cone region 24 is concave in this embodiment and comprises the inner most region of bit 10 (e.g., cone region 24 is the central most region of bit 10). Adjacent cone region 24 is shoulder (or the upturned curve) region 26. Next to shoulder region 26 is the gage region 28 which is the portion of the bit face 20 which defines the outer radius 23 of bit 10. Outer radius 23 extends to and therefore defines the full gage diameter of bit 10.

Still referring to FIG. 2, cone region 24 is defined by a radial distance along the x-axis measured from central axis 11. It is understood that the x-axis is perpendicular to central axis 11 and extends radially outward from central axis 11. Cone region 24 may be defined by a percentage of outer radius 23 of bit 10. Cone region 24 may likewise be defined by the location of one or more secondary blades. For example, cone region 24 extends from central axis 11 to a distance at which a secondary blade begins (e.g., distance “D” illustrated in FIG. 3). In other words, the outer boundary of cone region 24 may coincide with the distance “D” at which one or more secondary blades begin. The actual radius of cone region 24, measured from central axis 11, may vary from bit to bit depending on a variety of factors including without limitation, bit geometry, bit type, location of one or more secondary blades, location of backup cutter elements 50, or combinations thereof.

Blade profiles 39 and bit face 20 may also be described as two regions termed “inner region” and “outer region”, where the “inner region” is the central most region of bit 10 and is analogous to cone region 24, and the “outer region” is simply the region(s) of bit 10 outside the inner region. Using this nomenclature, the outer region is analogous to the combined shoulder region 26 and gage region 28 previously described. The inner region may be defined similarly to cone region 24.

Downwardly extending flow passages 21 have nozzles or ports 22 disposed at their lowermost ends. Bit 10 may include multiple flow passages 21 and nozzles 22. The flow passages 21 are in fluid communication with central bore 17. Together, passages 21 and nozzles 22 serve to distribute drilling fluid around the cutter elements 40 for flushing drilled formation from the bottom of the borehole away from the cutting faces 44 (FIG. 1) of cutter elements 40 during drilling. Among several other functions, the drilling fluid also serves to cool the cutter elements 40 during drilling.

Referring to FIGS. 3 and 4, the cutting face 412 of the bit shown includes six blades 420-425. Each blade includes a plurality of cutting elements or cutters generally disposed radially from the center of cutting face 412 to generally form rows. The radial position of each cutter on the drill bit in rotated profile is shown in FIG. 4. The cutting face 515 has a central depression or cone region 514, a gage region 516 and a shoulder region 512 therebetween. The highest point (as drawn) on the cutter tip profiles defines the bit nose 517. Three cutter profiles are labeled 510, 520, and 530. It will be seen that certain cutters, although at differing axial positions as shown in FIG. 3, may occupy radial positions that are in similar radial position to other cutters on other blades. Cutting profile 510, for example, as applied to a drill bit as shown in FIG. 3, corresponds to a single trough cut by multiple cutting elements.

Further, as shown in FIG. 3, a fixed cutter drill bit may include primary blades 420, 426 and secondary blades 421, 422, 424, 425. Primary blades 420, 426 are generally defined as blades that extend from a bit center area or cone region (514 in FIG. 4), substantially proximal a central axis of the bit, to a gage region (516 in FIG. 4). Secondary blades 421, 422, 424, 425 are generally defined as blades that are spaced between the primary blades and begin a radial distance D from the central axis and extend to the gage region. Each primary blade may include primary cutters or a combination or primary cutters and backup cutters. Similarly, each secondary blade may include primary cutters or a combination of primary cutters and backup cutters.

Referring now to FIGS. 5A and 5B, schematics of conventional blade layouts or configurations on a drill bit are shown. As shown, a drill bit may include a plurality of primary blades 550 and a plurality of secondary blades 552 disposed in between the primary blades 550. An angle α between primary blade 550 and secondary blade 552 may be varied to change the bit dynamics, for example to balance the bit. In particular, the angles α between the blades 550, 552 may be varied to adjust the resultant forces acting on the bit during drilling. Based on the determined bit dynamics, the blades may be arranged in varying configurations to change, for example, rate of penetration (ROP) or force distribution on the bit. However, in adjusting the angles of the blades other aspects of bit performance, such as bit hydraulics, may be adversely affected.

Accordingly, there exists a need for means for providing greater flexibility in addressing various aspects of bit performance, including bit balance, bit hydraulics, and ROP, and greater flexibility in varying diamond density and/or cutter density across a bit face.

SUMMARY OF INVENTION

In one aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a nose region, a shoulder region, and a gage region, at least one disjointed blade disposed on the bit face, the disjointed blade including a first section beginning proximate a central axis of the bit and extending less than full gage, and a second section beginning a selected distance from the central axis and extending to full gage, and a plurality of cutting elements mounted on the at least one disjointed blade.

In another aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a nose region, a shoulder region, and a gage region, at least one disjointed primary blade disposed on the bit face, the disjointed blade including a first section disposed primarily in the cone region, and a second section disposed primarily in at least one of the nose, shoulder, and gage regions, and at least one cutting element disposed on the first section and at least one cutting element disposed on the second section.

In another aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a shoulder region, and a gage region, at least one blade disposed on the bit face, the blade beginning a selected distance from the central axis and extending to full gage, at least one cutting structure disposed on the bit face in the cone region, and at least one cutting element disposed on the at least one blade.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a conventional drill bit.

FIG. 2 is a partial cross-sectional view of a conventional drill bit with cutting elements of the bit shown rotated into a single profile.

FIG. 3 is a top view of a conventional drill bit.

FIG. 4 is a rotated profile view of cutting elements mounted on a conventional drill bit.

FIGS. 5A and 5B are schematics of blade layouts on conventional drill bits.

FIG. 6 is a partial cross-sectional view of a blade of a drill bit.

FIGS. 7A and 7B are schematics of blade configuration on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 8 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 9 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 10 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 11 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 12 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 13 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 14 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 15 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 16 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 17 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 18 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 19 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 20 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 21 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 22 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 23 is a schematic of blade configurations on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 24 is a rotated profile view of cutting elements mounted on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 25 is a rotated profile view of cutting elements mounted on a drill bit formed in accordance with embodiments of the present disclosure.

FIG. 26 is a rotated profile view of cutting elements mounted on a drill bit formed in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation. More specifically, embodiments disclosed herein relate to fixed cutter drill bits, particularly, PDC drill bits.

Embodiments of the present disclosure provide a drill bit for drilling a borehole in a formation. In particular, drill bits formed in accordance with embodiments disclosed herein provide fixed cutter drill bit with a unique blade configuration that may provide enhanced bit balance and improved bit hydraulics, as well as increased ROP. Additionally, drill bits formed in accordance with embodiments disclosed herein greater flexibility in varying diamond density and/or cutter density across a bit face.

Generally speaking, a fixed cutter bit includes a bit body having a central axis 661 and a bit face 665 that may be divided into four regions. Namely, the bit face includes a cone region 656, a nose region 657, a shoulder region 658, and a gage region 659, as shown in FIG. 6A. The cone region 656 is concave in this embodiment and includes the inner most region of bit (e.g., the cone region is the central most region of bit 10). The nose region 657 is adjacent the cone region, starting where the upward turn of the cone region 656 transitions to a convex curve of the bit face. The highest point (as drawn) on the cutter tip profiles defines the bit nose. Adjacent the nose region 657 is the shoulder (or the outer curve) region 658. One of ordinary skill in the art will appreciate that the nose region 657 and the shoulder region 658 may, in some instances, be collectively referred to as the shoulder region. Next to the shoulder region 658 is the gage region 659, which is the portion of the bit face that defines the outer radius 663 of bit 10. Outer radius 663 extends to and therefore defines the full gage diameter of bit 10. As used herein, the terms “full gage diameter” or “full gage” are used to describe elements or surfaces extending to the full, nominal gage of the bit diameter.

Referring to FIGS. 7A and 7B, schematics of blade layouts on a drill bit formed in accordance with embodiments of the present disclosure are shown. In this embodiment, a drill bit (not shown) includes a bit face, generally indicated at 771, having a cone region, a nose region, a shoulder region, and a gage region. Three disjointed blades 770 a, 770 b, 770 c, angularly-spaced apart, are disposed on the bit face 771. Each disjointed blade 770 includes two sections, a first section 772 and a second section 774, separated or disconnected from one another. Thus, as used herein, “disjointed blade” refers to a blade formed from two or more separate or disconnected blade sections. The first section 772 of each disjointed blade 770 begins proximate a central axis A and extends less than full gage, as denoted by the bit diameter 775. The second section 774 of each disjointed blade 770 begins a selected distance from the central axis A and extends to full gage, denoted by bit diameter 775. As shown, the second sections 774 of disjointed blades 770 may be disposed on bit face 771 at a different angle than the first section 772 with respect to the direction of rotation, indicated at 777, of the bit (see in particular first and second sections 772, 774 of disjointed blade 770 a). Further, because the disjointed blades 770 include two separate sections 772, 774, the sections 772, 774 may be disposed on the bit face 771 in different radial planes, i.e., the second section 774 may be disposed in a plane behind the radial plane of the first section 772 with respect to the direction of rotation, indicated at 777.

As shown in FIGS. 7A and 7B, disjointed blades 770 are primary blades. In particular, each disjointed blade 770 a, 770 b, 770 c is at least partially disposed in the cone region of the bit face. In some embodiments, each disjointed blade 770 a, 770 b, 770 c, as a whole, extends from a location proximate the central axis of the A of the bit to a location less than full gage. In other embodiments, each disjointed blade 770 a, 770 b, 770 c, as a whole, extends from a location proximate the central axis of the A of the bit to full gage. In one embodiment, the first section 772 of the disjointed blade 770 extends from a location proximate the central axis A to a first location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face. In this embodiment, the second section 774 of the disjointed blade 770 extends from a second location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face to full gage (669 in FIG. 6). The radial length to the first and second locations may be equal if the second section 774 is disposed behind the first section 772 with respect to a direction of rotation, indicated at 777, of the bit. Otherwise, the radial length to the first and second locations must be unequal, so as to provide a gap or disconnect between the first and second sections 772, 774 of the disjointed blade 770.

Disjointed blades 770 may be uniformly spaced around the bit face 771 or may be variably spaced about the bit face 771. Further, although three disjointed primary blades 770 are shown in FIGS. 7A and 7B, one of ordinary skill in the art will appreciate that that any number of primary blades or disjointed primary blades may be disposed on a bit face without departing from the scope of embodiments disclosed herein. For example, two primary blades or four primary blades may be disposed on the bit face 771. Further, in these examples, one or more of the primary blades, but not all of the primary blades, may be disjointed blades. Further, as will be discussed in more detail below, each disjointed blade may include two, three, or more separate sections.

In an embodiment where two or more primary blades are disjointed blades, the relationship between the first section and second section of the first disjointed blade may differ from the relationship between the first section and second section of the second disjointed blade. For example, the first disjointed blade may include a first section and a second section, wherein the second section is radially spaced a selected distance away from the first section and is disposed at a different angle on the bit face with respect to the direction of rotation of the bit. In contrast, the second disjointed blade may include a first section and a second section, wherein the second section is disposed at the same angle as the first section, but is disposed on a different radial plane than the first section, i.e., behind the first section with respect to the direction of rotation of the bit.

In accordance with embodiments disclosed herein, each blade on the fixed cutter may be independently designed. Thus, a fixed cutter bit may include a combination of one or more of solid primary blades (i.e., conventional blades), disjointed primary blades, and secondary blades. Further, each disjointed blade may be independently designed based on the disjointed angle between the two sections of the disjointed blade, the radial plane(s) on which each section is disposed, and the number of sections included in each disjointed blade.

Secondary blades 776 may be disposed between two disjointed blades 770. In some embodiments two or more secondary blades 776 may be disposed between two disjointed blades 770. Further, secondary blades 776 may be disposed between a disjointed blade 770 and a solid (conventional) primary blade (not shown). As shown, secondary blades 770 do not extend from a location proximate central axis A. Rather, each secondary blade 776 extends from a distance D away from central axis A to the periphery of the bit, or full gage (669 in FIG. 6). Secondary blades 776 may be uniformly spaced around the bit face 771 or may be variably spaced. Further, secondary blades 776 may be disposed at varying angles with respect to the primary or disjointed blades 770.

The design of the disjointed blades 770, including, for example, number of disjointed blades, number of sections, angle between the sections, gap size between the sections, and radial planes of the sections, may be selected so as to provide improved bit hydraulic efficiency. For example, the design of the disjointed blades 770 facilitates the placement of nozzles 778 in desired areas of the bit face 771. Because the primary blades of the bit may include disjointed blades, wherein first and second sections may be disposed separate from one another, greater flexibility in the placement of nozzles is provided.

Referring now to FIG. 8, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 881, having a cone region 841, a nose region 842, a shoulder 843 region, and a gage region 844. In this embodiment, three disjointed blades 880 a, 880 b, 880 c are uniformly disposed on the bit face 881 and each disjointed blade 880 includes two sections, a first section 882 and a second section 884, separated or disconnected from one another. The first section 882 of each disjointed blade 880 is disposed primarily in the cone region 841 of the bit face 881. The second section, 884 is disposed primarily in the nose, shoulder, and gage regions 842, 843, 844 of the bit face. In particular, the first section 882 of disjointed blade 880 begins proximate a central axis A of the bit and extends to a location proximate the outer circumferential edge 666 of the cone region of the bit face 881 and the second section 884 begins at a second location proximate the outer circumferential edge 666 of the cone region of the bit face and extends full gage 669. As shown, the second section 884 of the disjointed blade 880 is disposed along a radial plane behind the radial plane of first section 882 with respect to a direction of rotation of the bit, indicated at 888.

As depicted, each section of the disjointed blades 880 a, 880 b, 880 c includes at least one cutting element 883 mounted thereon. The cutting elements 883 may be formed having a substrate or support stud made of carbide, for example, tungsten carbide, and an ultra hard cutting surface layer or table made of a polycrystalline diamond material or a polycrystalline boron nitride material deposited onto or otherwise bonded to the substrate at an interface surface. One of ordinary skill in the art will appreciate that any cutting element known in the art for use on a fixed cutter drill bit may be used without departing from the scope of embodiments disclosed herein. Additionally, although depicted as a single row of cutters on each section of the disjointed blade 880, multiple rows of cutters may be disposed on a single section of a single disjointed blade 880.

Referring still to FIG. 8, one of ordinary skill in the art will appreciate that each region (cone 841, nose 842, shoulder 843, gage 844) of the bit face 881, may be characterized by a proximal boundary and a distal boundary with respect to the central axis A. For example, cone region 841 is characterized by a proximal boundary located near or coinciding with the central axis A. A cone distal boundary 866 is located radially outward from the cone proximal boundary and encloses the cone region 841. The nose region 842 is located radially adjacent the cone region 841, abutting the cone distal boundary 866, and extends to a nose distal boundary 867. Thus, a nose proximal boundary coincides with the cone distal boundary 866. The shoulder region 843 is located radially adjacent the nose region 842, abutting the nose distal boundary 867, and extends to a shoulder distal boundary 868. Thus, the shoulder proximal boundary coincides with the nose distal boundary 867. The gage region 844 is located radially adjacent the shoulder region 843, abutting the shoulder distal boundary, and extends to a gage distal boundary 869. Thus, the gage proximal boundary coincides with the shoulder distal boundary 868.

As discussed above, a disjointed blade in accordance with embodiments disclosed herein may include two or more section disposed on the bit face. In one embodiment, a first section of the disjointed blade may extend from the proximal boundary of the cone region to the distal boundary of the cone region and a second section may extend from the proximal boundary of the nose region to the distal boundary of gage region, i.e., full gage. In an embodiment where a disjointed blade includes four sections, the first section may extend from the cone proximal boundary to the cone distal boundary, the second section may extend from the nose proximal boundary to the nose distal boundary, the third section may extend from the shoulder proximal boundary to the shoulder distal boundary, and the fourth section may extend from the gage proximal boundary to the shoulder distal boundary. As will be discussed below with reference to the figures, each section may be disposed at varying angles and/or place along the same or different radial planes.

In other embodiments, a blade section of disjointed blade may overlap another section of the disjointed blade. For example, considering a disjointed blade with two sections, the first section may extend from the cone proximal boundary to the cone distal boundary. The second section may be disposed on a radial plane behind the first section, with respect to the direction of rotation of the bit, and extend from a location radially inward from the cone distal boundary and extend to full gage. Thus, a portion of the second section overlaps or trails the first section. Examples of various configurations of drill bits formed in accordance with embodiments of the present disclosure are described in more detail below.

Referring now to FIG. 9, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 991, having a cone region, a nose region, a shoulder region, and a gage region. In this embodiment, three disjointed blades 990 a, 990 b, 990 c are uniformly disposed on the bit face 991 and each disjointed blade 990 includes two sections, a first section 992 and a second section 994, separated or disconnected from one another. The first section 992 of each disjointed blade 990 is disposed primarily in the cone region of the bit face 991. The second section 994 is disposed primarily in the nose, shoulder, and gage regions of the bit face. In particular, the first section 992 of disjointed blade 990 begins proximate a central axis A of the bit and extends to a location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face and the second section 994 begins at a second location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face and extends full gage (669 in FIG. 6). As shown, the second section 994 of the disjointed blade 990 is disposed along a radial plane behind the radial plane of first section 992 with respect to a direction of rotation of the bit, indicated at 999.

Three secondary blades 996 are spaced uniformly between each disjointed blade 990 around the bit face 991. The secondary blades 996 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in FIG. 9, the secondary blades 996 start outside the cone region, i.e., in the nose region, and may extend out less than full gage or to full gage.

Referring to FIG. 10, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 1001, having a cone region, a nose region, a shoulder region, and a gage region. In this embodiment, three disjointed blades 1000 a, 1000 b, 1000 c are disposed on the bit face 1001 and each disjointed blade 1000 includes two sections, a first section 1002 and a second section 1004, separated or disconnected from one another. The first sections 1002 of disjointed blades 1000 a, 1000 b are disposed primarily in the cone region of the bit face 1001. The first section 1002 of the third disjointed blade 1000 c starts proximate the central axis A and extends less than full gage.

The second sections 1004 of all three disjointed blades 1000 are disposed primarily in the nose, shoulder, and gage regions of the bit face. In particular, the second sections 1004 begin at a location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face 1001 and extend full gage (669 in FIG. 6). As shown, the second section 1004 of the disjointed blade 1000 is disposed along a radial plane behind the radial plane of first section 1002 with respect to a direction of rotation of the bit, indicated at 1010. A plurality of cutters 1003 are disposed on each section 1002, 1004 of the disjointed blades 1000.

As shown, the first section 1002 of the third disjointed blade 1000 c extends out past the cone region and the second section 1004 starts proximate the outer circumferential edge (666 in FIG. 6) of the cone region behind the first section 1002, with respect to the direction of rotation of the bit. Thus, at least one cutter 1003 disposed on the second section 1004 of the third disjointed blade 1000 c trails at least one cutter 1003 disposed on the first section 1002 of the third disjointed blade 1000 c. In other words, at least one cutter 1003 on the second section 1004 is disposed at the same radial distance from the central axis A as a cutter 1003 on the first section 1002 of the same disjointed blade, but on a different radial plane, thereby creating an overlap of the cutters 1003.

Three secondary blades 1006 are spaced between each disjointed blade 1000 around the bit face 1001. The secondary blades 1006 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in FIG. 10, the secondary blades 1006 start outside the cone region, i.e., in the nose region, and may extend out less than full gage or to full gage.

Referring to FIG. 11, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 1101, having a cone region, a nose region, a shoulder region, and a gage region. In this embodiment, three disjointed blades 1100 a, 1100 b, 1100 c are disposed on the bit face 1101. First and third disjointed blades 1100 a, 1100 c include two sections, a first section 1102 and a second section 1104, separated or disconnected from one another. Second disjointed blade 1000 b includes three sections, a first section 1002, a second section 1104 and a third section 1105.

The first section 1102 of first disjointed blade 1000 a is disposed primarily in the cone region of the bit face 1101. The second section 1104 of the first disjointed blade 1100 a is disposed primarily in the nose, shoulder, and gage regions of the bit face. In particular, the second section 1104 begins at a location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face 1101 and extends full gage (669 in FIG. 6). As shown, the second section 1104 of the first disjointed blade 1100 a is disposed along a radial plane behind the radial plane of first section 1102 with respect to a direction of rotation of the bit, indicated at 1111.

The first section 1102 of the second disjointed blade 1100 b is disposed primarily in the cone region of the bit face 1101. The second section 1104 of the second disjointed blade 1100 b is disposed primarily in the nose, shoulder, and gage regions of the bit face 1101. In particular, the second section 1104 begins at a location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face 1101 and extends less than full gage. As shown, the second section 1104 of the second disjointed blade 1100 b is disposed along a radial plane behind the radial plane of first section 1102 with respect to a direction of rotation of the bit, indicated at 1111. The third section 1105 of the second disjointed blade 1100 b is disposed along the radial plane of the first section 1102 of second disjointed blade 1100 b. The third section 1105 extends from a selected distance from the central axis. For example, third section 1105 may extend from the outer circumferential edge of the nose region (667 in FIG. 6) or the outer circumferential edge of the shoulder region (668 in FIG. 6) to full gage. Thus, as a whole, second disjointed blade 1100 c, i.e., summing up first section 1102, second section 1104, and third section 1105, extends from proximate the central axis A to full gage.

The first section 1102 of the third disjointed blade 1100 c starts proximate the central axis A and extends into the nose region, but less than full gage. The second section 1104 of the third disjointed blade 1100 c is disposed primarily in the nose, shoulder, and gage regions of the bit face. In particular, the second section 1004 begins at a location proximate the outer circumferential edge (666 in FIG. 6) of the cone region of the bit face 1101 and extends full gage (669 in FIG. 6). As shown, the second section 1104 of the third disjointed blade 1100 c is disposed along a radial plane behind the radial plane of first section 1102 with respect to a direction of rotation of the bit, indicated at 1111.

Three secondary blades 1106 are spaced between each disjointed blade 1100 around the bit face 1101. The secondary blades 1106 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in FIG. 11, the secondary blades 1106 start outside the cone region, i.e., in the nose region, and may extend out less than full gage or to full gage.

Referring now to FIG. 12, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 1201, having a cone region, a nose region, a shoulder region, and a gage region. In this embodiment, two disjointed blades 1200 a, 1200 b are disposed on the bit face 1201 and each disjointed blade 1200 includes two sections, a first section 1202 and a second section 1204, separated or disconnected from one another. Additionally, a solid (conventional) primary blade 1207 is disposed on the bit face, angularly-spaced from the disjointed blades 1200.

The first sections 1202 of first and second disjointed blades 1200 a, 1200 b are disposed primarily in the cone region of the bit face 1201. The second sections 1204 of the two disjointed blades 1200 are disposed primarily in the nose, shoulder, and gage regions of the bit face 1201. As shown, the second sections 1204 of the first and second disjointed blades 1200 a, 1200 b are disposed along a radial plane behind the radial plane of first section 1202, with respect to a direction of rotation of the bit, indicated at 1212. The solid (conventional) primary blade 1207 starts proximate the central axis A and extends to full gage.

Four secondary blades 1206 are spaced between disjointed blade 1200 and solid (conventional) primary blade 1207 around the bit face 1201. The secondary blades 1206 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in FIG. 12, the secondary blades 1206 start outside the cone region, i.e., in the nose region, and may extend out less than full gage or to full gage.

Referring to FIG. 13, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 1301, having a cone region, a nose region, a shoulder region, and a gage region. In this embodiment, three disjointed blades 1300 a, 1300 b, 1300 c are disposed on the bit face 1301 and each disjointed blade 1300 includes two sections, a first section 1302 and a second section 1304, separated or disconnected from one another. The first sections 1302 of disjointed blades 1300 are disposed primarily in the cone region of the bit face 1301.

The second sections 1304 of the disjointed blades 1300 are disposed a selected distance away from the central axis A and extend to full gage. The second section 1304 of the disjointed blade 1300 is disposed along a radial plane behind the radial plane of first section 1302 with respect to a direction of rotation of the bit, indicated at 1310. As shown, the selected distance from the central axis A, at which the second sections 1304 start, is disposed behind the first section 1302 with respect to the direction of rotation 1313 of the bit. Therefore, first and second sections 1302, 1304 of disjointed blades 1300 overlap in their radial distance from central axis A. Accordingly, at least one cutter 1303 disposed on the second sections 1304 of the disjointed blades 1300 may trail at least one cutter 1303 disposed on the first sections 1302 of the disjointed blades 1300.

Three secondary blades 1306 are spaced between each disjointed blade 1300 around the bit face 1301. The secondary blades 1306 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in FIG. 13, the secondary blades 1306 start outside the cone region, i.e., in the nose region, and may extend out less than full gage or to full gage.

Referring to FIG. 14, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 1401, having a cone region, a nose region, a shoulder region, and a gage region. In this embodiment, three disjointed blades 1400 a, 1400 b, 1400 c are disposed on the bit face 1401 and each disjointed blade 1300 includes three sections, a first section 1402, a second section 1404, and a third section 1405, separated or disconnected from one another. The first sections 1402 of disjointed blades 1400 are disposed primarily in the cone region of the bit face 1401. The second sections 1404 of disjointed blades 1400 are disposed primarily in the nose and shoulder regions of the bit face 1401. The third sections 1405 of disjointed blades 1400 are disposed primarily in the gage section of the bit face 1401.

As shown, the second sections 1404 are disposed on a radial plane different from the radial plane of the first sections 1402. The third sections 1405 are disposed on a radial plane different from the radial planes of the first and second sections 1402, 1404. Further, as shown, the second sections 1404 trail the first sections 1402, and the third sections 1405 trail the second sections 1404. Thus, as shown, one or more disjointed sections of one or more of the disjointed blades may overlap in the radial distance from the central axis A.

Three secondary blades 1406 are spaced between each disjointed blade 1400 around the bit face 1401. The secondary blades 1406 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in FIG. 134, the secondary blades 1406 start outside the cone region, i.e., in the nose region, and may extend out less than full gage or to full gage.

Referring now to FIGS. 15-17, a blade layout formed on a drill bit in accordance with embodiments of the present disclosure is shown. The drill bit (not shown) includes a bit face, generally indicated at 1501, having a cone region, a nose region, a shoulder region, and a gage region. In one embodiment, a single cutting structure 1542 may be disposed in the cone region of the bit face 1501. In this embodiment, the single cutting structure 1542 may be a block of material or a single blade. The single cutting structure may be formed from any material known in the art, for example, tungsten carbide, alloys, polycrystalline diamond and polycrystalline cubic boron nitride, or other ultrahard materials. The cutting structure 1542 may be formed in various shapes and sizes. For example, the cutting structure 1542 may have a circular cross-section, as shown in FIG. 15, or may have a cross-like cross-section, as shown in FIGS. 16 and 17. Elements 1513 may be disposed on cutting structure 1542. Elements 1513 may include diamond impregnated inserts, tungsten carbide inserts, depth of cut limiters, or other elements configured to cut formation, reduce wear, or stabilize the bit.

In some embodiments, one or more elements may be disposed in the cone region of the bit face 1501 without a blade or other structure. Elements may include, for example, diamond impregnated inserts, tungsten carbide inserts, depth of cut limiters, or other elements configured to cut formation, reduce wear, or stabilize the bit. Additionally, the surface of the bit face 1501 in the cone region may include a layer of ultra hard material disposed thereon. One or more blades may be disposed on the bit face primarily in the nose, shoulder, and gage regions, outside the cone region. In particular, a plurality of blades may be angularly-spaced around the bit face, each extending from a selected distance from the central axis A to less than full gage or full gage.

As shown in FIGS. 18-22, fixed cutter drill bits formed in accordance with embodiments of the present disclosure provide means for varying the diamond density between the various regions of the bit face, i.e., cone, nose, shoulder, and gage regions. Diamond density, as used herein, refers to the amount of diamond material, i.e., PDC cutters or other polycrystalline diamond coatings, in a specific region. Fixed cutter drill bits having disjointed blades 1800 may be configured such that the diamond density in the cone region is less than the diamond density in the nose, shoulder, and gage regions (e.g., FIG. 18). Additionally, drill bits having disjointed blades 1800 may be configured to provide a predetermined diamond density ratio between, for example, the cone region and the combined nose, shoulder, gage region or between each individual region: cone region, nose region, shoulder region, gage region. Thus, varying the configuration of the disjointed blades, including, for example, number of sections, locations, and number of cutters on each section, and any secondary blades on the bit face can change the diamond density of the regions of the bit face. For example, the diamond density of the cone region may be increased by disposing a second section of a disjointed blade behind a first section of a disjointed blade, such that cutting elements of the second section trail cutting elements of the first section, as shown in FIG. 14. The diamond density may be adjusted in order to improve bit performance, for example, ROP.

With reference to FIG. 23, drill bits formed in according with embodiments disclosed herein, having at least one disjointed blade 2300 on a bit face 2301, provides greater flexibility in placement options for hydraulics. In particular, blade configurations in accordance with embodiments disclosed herein provide more options for nozzle locations 2350 on the bit face 2301, thereby enhancing bit hydraulics.

Referring to FIGS. 24-27, rotated profile views of cutting elements mounted on drill bits formed in accordance with embodiments of the present disclosure is shown. As shown in FIG. 24, in one embodiment, a fixed cutter drill bit having at least one disjointed blade may be configured in such a way that the rotated profile provides full coverage and is similar to a conventional rotated profile view (e.g., FIG. 4). In other embodiments, as shown in FIG. 25, a fixed cutter drill bit having a least one disjointed blade may be configured such that the rotated profile view of the cutting elements results in a dip or concave curve in the shoulder region of the bit face. In yet other embodiments, as shown in FIG. 26, a fixed cutter drill bit having a least one disjointed blade may be configured such that the rotated profile view of the cutting elements results in a gap or break between the nose region and shoulder region of the bit face. One of ordinary skill in the art will appreciate that the rotated profile views shown in FIGS. 24-26 are merely exemplary, and that various different rotated profile views may be generated by a bit formed with a blade configuration in accordance with embodiments of the present disclosure.

While reference to bits having three disjointed blades has been made, one of ordinary skill in the art will appreciate that bits having one or more disjointed blades may also be used without departing from the scope of embodiments disclosed herein. Additionally, one of ordinary skill in the art will appreciate that bits formed in accordance with embodiments of the present disclosure may have any number of secondary blades, even zero.

Disjointed blades formed in accordance with the present disclosure may include two or more discrete sections. In alternate embodiments, the surface of the bit may be slightly contoured or raised in between the two or more sections of a disjointed blade. For example, a disjointed blade may include a filleted relief between the axial ends of the sections. Such webbing or contouring between the sections of the disjointed blades may reduce blade cracking or crack propagation.

Advantageously, embodiments disclosed herein provide greater flexibility in addressing various aspects of bit performance, including bit balance and bit hydraulics. In particular, fixed cutter drill bits formed in accordance with embodiments disclosed herein may provide more stabile and/or balanced bits. Further, fixed cutter drill bits formed in accordance with embodiments disclosed here may provide increased bit hydraulics.

Embodiments of the present disclosure provide various blade configurations for a fixed cutter bit that may separate the mechanics of the cone region of the bit face from the nose, shoulder, and gage regions of the bit face. Advantageously, a bit in accordance with embodiments disclosed herein, can therefore be designed that may provide full coverage, bit stability, and improved bit hydraulics. Additionally, sections of disjointed blades formed in accordance with embodiments disclosed herein may be selected so as to provide depth of cut limits or control of the bit when drilling.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims. 

1. A drill bit for drilling a borehole in a formation, the drill bit comprising: a bit body having a bit face comprising a cone region, a nose region, a shoulder region, and a gage region; at least one disjointed blade disposed on the bit face, the disjointed blade comprising: a first section beginning proximate a central axis of the bit and extending less than full gage, and a second section beginning a selected distance from the central axis and extending to full gage; and a plurality of cutting elements mounted on the at least one disjointed blade.
 2. The drill bit of claim 1, further comprising at least one secondary blade, the secondary blade beginning a predetermined distance from the central axis and extending to full gage.
 3. The drill bit of claim 1, wherein the disjointed blade further comprises a third section beginning a second selected distance from the central axis and extending less than full gage.
 4. The drill bit of claim 1, wherein the second section is disposed on a radial plane of the first section.
 5. The drill bit of claim 1, wherein the second section behind a radial plane of the first section.
 6. The drill bit of claim 5, wherein a cutting element disposed on the second section trails a cutting element disposed on the first section.
 7. The drill bit of claim 1, wherein the first section is primarily disposed in the cone region.
 8. The drill bit of claim 3, wherein the second section is primarily disposed in the nose and shoulder regions and the third section is primarily disposed in the gage region.
 9. A drill bit for drilling a borehole in a formation, the drill bit comprising: a bit body having a bit face comprising a cone region, a nose region, a shoulder region, and a gage region; at least one disjointed primary blade disposed on the bit face, the disjointed blade comprising: a first section disposed primarily in the cone region, and a second section disposed primarily in at least one of the nose, shoulder, and gage regions; and at least one cutting element disposed on the first section and at least one cutting element disposed on the second section.
 10. The drill bit of claim 9, wherein the second section partially overlaps the first section in a radial direction.
 11. The drill bit of claim 9, wherein the at least one disjointed primary blade further comprises a third section disposed primarily in at least one of the nose, shoulder, and gage regions.
 12. The drill bit of claim 9, wherein the second section is disposed on a radial plane of the first section.
 13. The drill bit of claim 11, wherein the third section is disposed on a radial plane of the first section.
 14. A drill bit for drilling a borehole in a formation, the drill bit comprising: a bit body having a bit face comprising a cone region, a shoulder region, and a gage region; at least one blade disposed on the bit face, the blade beginning a selected distance from the central axis and extending to full gage; at least one cutting structure disposed on the bit face in the cone region; and at least one cutting element disposed on the at least one blade.
 15. The drill bit of claim 15, wherein the at least one blade begins at an outer circumference of the cone region.
 16. The drill bit of claim 15, wherein the at least one blade is disposed primarily in the nose, shoulder, and gage regions. 